Freely rotatable hydraulic pivot element

ABSTRACT

The freely rotatable hydraulic pivot element for an internal combustion engine has four oil inlets which are in fluid communication with the lash adjusting element inside the pivot element and in fluid communication with the oil gallery by using four more equally spaced oil inlets in the outer housing of the cylinder head while still in fluid communication therein. The use of four or more oil inlets are in the same radial plane of the outside cylindrical housing of the pivot element.

FIELD OF THE INVENTION

This invention relates to internal combustion engines and, more particularly, to hydraulic pivot elements such as lash adjusters which are employed in the valve train of an internal combustion engine.

BACKGROUND OF THE INVENTION

Hydraulic pivot elements such as lash adjusters and switchable hydraulic pivot elements require hydraulic fluid, such as oil, for normal operation. In the case of the switchable element, hydraulic fluid is also necessary for coupling and uncoupling the hydraulic lash adjuster from the housing.

Typically, in overhead cam engines, the hydraulic fluid is provided to the hydraulic pivot element by means of an oil gallery. In the case of a switchable hydraulic pivot element there are two oil galleries, one for the lash adjuster and one for the coupling elements of the switchable element so as to couple and uncouple the coupling elements.

In order to provide for fluid communication between the pivot element and the oil galleries, two solutions have been employed in the past. One solution is to provide oil grooves in the outer housing of the pivot elements. These oil grooves allow for the pivot element to freely rotate within the bore of the cylinder heads while providing hydraulic fluid from the oil gallery to the oil inlet of the pivot element. FIG. 1 illustrates a typical pivot element 10 having outer housing 11 having three oil grooves labeled 12, 14, an 16 for providing oil to oil inlets 18, 20, and 22. As will be appreciated, forming oil grooves 12, 14, and 16 reduces the thickness of outer housing 11 and therefore reduce the overall strength of outer housing 11.

The second solution for providing oil communication between the oil galleries of the cylinder head and the pivot element is to provide an orientation device in the outer housing of the pivot element. Typically such an orientation device is made up of a hole or axial groove in the outer housing of the pivot element and a corresponding hole or outer groove in the bore of the cylinder head in which the pivot element is mounted. A key or pin bridges the two grooves or holes so as to maintain the orientation of the pivot element in the bore of the cylinder and prevent rotation. By maintaining the orientation, proper alignment between the inlets in the outer housing of the pivotal element and the oil gallery is ensured. One of the problems with such an orientation mechanism is that is requires additional work in order to form the two holes/grooves and to insert the key element and orient the pivot element in the cylinder head.

OBJECTS OF THE INVENTION

The object of the invention is to simplify the design of the prior art and to eliminate the oil grooves in the outer housing of the pivot element and to eliminate the orientation device, while allowing for free rotation of the pivot element in the bore of the cylinder head and fluid communication between the inlets of the pivot element and the oil galleries.

These and other objects of the present invention will be more readily understood by reference to the following description.

SUMMARY OF THE INVENTION

The objects of the present invention are achieve by employing four or more oil ports in the outer cylindrical housing of the hydraulic pivot element wherein the ports are positioned in the same radial plane of the housing and spaced radially around the housing such that at least one of the oil ports is always in fluid communication with the corresponding oil gallery. The plurality of oil ports can be employed for the oil inlet for the hydraulic lash adjuster, the oil inlet of the coupling element, and the oil outlets.

Broadly, the present invention can be defined as a freely rotatable hydraulic pivot element for an internal combustion engine, wherein the element is mounted in a bore of the cylinder head to provide lash adjustment to a valve train of the engine and a first oil gallery for providing hydraulic fluid to the element, the gallery in fluid communication with the bore, the element comprising:

an outer cylindrical housing freely rotatable in the bore, the housing having a blind bore therein;

hydraulic piston member mounted in said blind bore for lash adjustment of the valve train, said piston member including a piston head for contact with a finger follower of said valve train, said piston head extending through the open end of said blind bore;

four or more first oil inlets in said outer housing, said first oil inlets in fluid communication with said hydraulic piston member in said blind bore, each of said first oil inlets bisection the same radial plane and said first oil inlets positioned radially around said outer housing such that as the element freely rotates in said bore, at least one of said first oil inlets is in fluid communication with said first oil gallery.

Preferably, the first oil inlets are space at equal radial distances around the outer housing. In other words, the first oil inlets are equidistant around the outer housing.

It is also preferred that each of the oil inlets is circular in shape and that the center of each of these circles is in the same radial plane. Preferably, this radial plane, is perpendicular to the axis of outer cylindrical housing.

Preferably, the outer housing has four or more oil outlets to allow hydraulic fluid to leave the blind bore of the outer cylindrical housing. Preferably, these outlets are positioned radially around the outer housing such that the outer housing can freely rotate and at least one of the outlets is in fluid communication with an outlet in said engine cylinder head.

In the case where the pivot element is switchable, the bore in the cylinder head has a second oil gallery positioned on a different radial plane than the first oil gallery so as to provide the necessary oil for the coupling mechanism of the pivot element. For a switchable pivot element, the pivot element further comprises

a coupling mechanism positioned in the blind bore below the hydraulic piston member to couple and uncouple the piston head from the housing;

a lost motion spring is positioned in the blind bore, below the coupling mechanism;

and four or more second oil inlets in the housing, the second oil inlets are in fluid communication with the coupling mechanism and are positioned for fluid communication with the second oil gallery, each of the second oil inlets bisect the same radial plane and the second oil inlets are positioned radially around the housing such that as the element freely rotates in the bore, at least one of the second oil inlets is in fluid communication with the second oil gallery.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a prior art hydraulic pivot element having oil grooves;

FIG. 2 is a perspective view of the hydraulic pivot element of the present invention;

FIG. 3 is a cross sectional view taken axially of the hydraulic pivot element of FIG. 2; and

FIG. 4 is a cross sectional view taken radially of a hydraulic pivot element having the locking mechanism of the present invention.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 2 illustrates a perspective view of hydraulic pivot element 30 according to the present invention having outer cylindrical housing 32 and piston head 34 extending from a hydraulic lash adjuster 36, a hydraulic piston member. First oil inlets 38 are illustrated in outer housing 32. In FIG. 2 only two of the four preferred first oil inlets are illustrated. Also illustrated in FIG. 2 are second oil inlets 40. FIG. 2 illustrates only two of the four preferred second oil inlets. Finally, oil outlets 42 are illustrated in FIG. 2. Of the preferred four oil outlets, only two are shown.

FIG. 3 illustrates an axial cross section of the hydraulic pivot element of FIG. 2. As can be seen, first oil inlet 38 is in fluid communication with first internal space 44. First internal space 44 completely surrounds the base of hydraulic lash adjuster 36. First internal space 44 is also in fluid communication with channel 46 and channel 46 is in fluid communication with second internal space 48 of hydraulic lash adjuster 36. Thus, hydraulic fluid is able to communicate the hydraulic lash adjuster 36 through first oil inlet 38.

Coupling mechanism 50 is a conventional coupling mechanism for a switchable lash adjuster and comprises piston 52 and piston 54 with spring 56 positioned there between. Spring 56 pushes pistons 52 and 54 out and into a locking engagement with outer cylindrical housing 32. Lost motion spring 58 is employed when hydraulic fluid is provided to second oil inlets 40. The oil provided to second oil inlets 40 causes pistons 52 and 56 to compress spring 56 and thereby unlock the coupling element 50 from outside housing 32 thereby uncoupling pivot element 30.

FIG. 4 is a radial cross section taken through coupling mechanism 50. As shown in FIG. 4, oil gallery 60 is in fluid communication with second oil inlets 40. When oil is passed through second oil inlets 40, it travels into channel 62. Channel 62 surrounds pistons 52 and 54 as shown in FIG. 3. The oil traveling in channel 62 is able to force pistons 52 and 54 back into the housing to thereby unlock hydraulic lash adjuster 36 from the outer cylindrical housing 32. It is noted that pistons 52 and 54 can be compressed even though they are not aligned with second oil inlets 40. As shown, oil gallery 60 is in engine block 64 and a portion of the outside of outer cylindrical housing 32 resides in gallery 60. A similar arrangement, as shown in FIG. 4, is employed for providing oil to first oil inlets 38.

As can be seen by the Figures the rotatable hydraulic pivot element of the present invention has no oil grooves in the exterior surface of the outer housing. This makes the outer housing stronger as well as allows for an overall reduction in the outer dimension of the outer housing. By reducing the overall outer dimension of the outer housing, in other words making the outer housing thinner, reduction in weight is obtained which translates into efficiency of the engine. This also allows for the internal diameter of the bore in the cylinder head to be reduced which can make a big difference in the bore of the pivot element since the bore of the pivot element in the cylinder head is typically very close to the valve springs and spark plugs. Reducing the outer diameter will increase the clearance to the valve springs and the spark plugs.

Furthermore, because of use of four or more oil inlets/oil outlets, no anti rotational feature is needed in the pivot element. Thus, the pivot element does not need to be oriented in the cylinder head.

REFERENCE CHARACTERS

-   10 pivot element, prior art -   11 outer housing -   12 oil groove -   14 oil groove -   16 inlet -   18 inlet -   20 inlet -   22 outlet -   30 pivot element -   32 outer cylindrical housing -   34 piston head -   36 hydraulic lash adjuster -   38 first oil inlets -   40 second oil inlets -   42 oil outlets -   44 first internal space -   46 channel -   48 second internal space -   50 coupling mechanism -   52 piston -   54 piston -   56 spring -   58 lost motion spring -   60 oil gallery -   62 channel -   64 engine block 

1. A freely rotatable hydraulic pivot element for an internal combustion engine wherein the element is mounted in a bore of the engine to provide lash adjustment to a valve train of the engine and a first oil gallery for providing hydraulic fluid to the element which is in fluid communication with the bore of the engine, the element comprising: an outer cylindrical housing freely rotatable in the bore of the engine, said housing having a blind bore therein; hydraulic piston member mounted in said blind bore for lash adjustment of the valve train, said piston member including a piston head for contact with a finger follower of said valve train, said piston head extending through the open end of said blind bore; four or more first oil inlets in said outer housing, said first oil inlets in fluid communication with said hydraulic piston parts in said blind bore, each of said first oil inlets bisecting the same radial plane, and said first oil inlets positioned radially around said outer housing such that as the element freely rotates in said bore, at least one of said first oil inlets is in fluid communication with said first oil gallery.
 2. The element of claim 1, wherein the first oil inlets are spaced at equal radial distances around said outer housing.
 3. The element of claim 1, wherein each of said first oil inlets is circular and the center of each circle of each of the inlets in the same radial plane.
 4. The element of claim 1, wherein the housing has four or more oil outlets for hydraulic fluid to leave said element.
 5. The element of claim 1, wherein the bore has a second oil gallery positioned on a different radial plane than the first oil gallery, said element further comprising a coupling mechanism positioned in said blind bore below said hydraulic piston member to couple and uncouple the piston head from the housing; a lost motion spring positioned in said blind bore below said mechanism; four or more second oil inlets in said housing, said second oil inlets in fluid communication with said coupling mechanism and for fluid communication with the second oil gallery, each of said second oil inlets bisecting the same radial plane, and said second oil inlets positioned radially around said housing such that as the element freely rotates in said bore, at lest one of the second oil inlets are in fluid communication with said second oil gallery. 